The invention relates to an unloading system for bulk material from a transport vessel, in particular a container, into a silo or another hopper.
Bulk goods have long been transported in standardised containers. The purpose is now to fill bulk goods in standardised loading devices and to convey them for transport on lorries, rail or ships. Containers are particularly suitable as loading devices. These containers are large capacity vessels for storing and for transporting goods which are of robust construction and sufficiently resistant to enable repeated use by several transporting and conveying means without transshipping the content. Such containers exist in many different sizes and are usually standardised.
The containers have moreover devices such as domed lids, discharge flaps and/or grains sliders, for easy transfer from one transport vessel to the other. The so-called ISO standard containers are the best known and the most widely used. These are mostly 20, 30 or 40-foot ship containers as well as swap-body systems. They enable to handle a major portion of merchandises and general cargo. The advantage lies in that the containers can be conveyed and transshipped quickly due to their standardised form and sizes with the most different transport means, such as ships, barges, railway cars and lorries.
Bulk material is often stored in silos and bunkers from which it can be removed and filled into such containers. Typical bulk materials are building materials such as top soil, sand, gravel, grit, cement, other mineral goods such as ore, road salt, and foodstuffs such as grain, sugar, food grade salt, coffee, flour as well as powdered goods such as pigments, filling materials, granules, pellets etc.
In terms of transport, we distinguish between continuous, uninterrupted flowing transport, for instance troughed belt conveyors and bucket conveyors as well as pneumatically fluid transport in air flows, For instance in bulk material compartments or bulk material bunkers of ships, in troughed and high fence vehicles, silo vehicles, lorries, railway wagons, etc. In bags, big bags, bulk ships, bulk containers and similar as transport vessels for light, individual goods or bulk goods.
Containers are usually cladded with a synthetic inliner, so-called container liner, which encloses the bulk material. Said container liner can be depressurised or pressurised and consequently prevents the destruction of the bulk material due to ist own humidity, as well as protects it against overheating, frost, contamination and attacks from parasites.
The transshipping and transport of bulk material is a costly and manifold process. To do so, the bulk material can be transported and unloaded as follows:
The bulk material is loaded on tipper trucks, for example railway wagons. They are then transported to another location and transshipped onto a loose goods ship. Said ship again travels to another location where the bulk material is packed in relatively small packs. Said sacks are palletised and again transported to another location, by means of lorries, railway wagons etc. to the end-user. The end-user may then store the bulk material delivered in sacks in a high silo, for example or send it directly for further processing. To do so, the sacks are slit and brought to the high silo.
A shortcoming of these multiple transshipments is the great risk of contaminating the bulk material or of mixing packaging components with the material when extracting it from its package.